iis application pool

Question

 i have a single application which i have hosted in iis in single application pool 

 when the number of user request increase the cpu utilization is more due to this i have getting error ..

 

1.) i have  google  and got the result to host sngle appliction in diffrent pool

 

2.) my idea to host  single application in three pools

 

i want to know  

 

1.) how iis will redirect to diffrent pool when the request are increased

2.)  how to monitor this

3.) how to do this 

 

 

your suggestion are most needfull